How long do the front and rear disc brakes last on the 335i. I am aware that you are to check for discoloration, scoring, etc and disc thickness. But for example, typically should the front or rear discs be changed every time the pads near changing? Or do the front discs usually get replaced every other brake pad change? Just wanted to get an idea on frequency.

My local Indy said BMW rotors are thin and do not get machined down. New front rotors each time with front pads. Rears you can get away with new rotors every other time when changing pads.

This is what my BMW Indy shop told me. I have not done brakes on my BMW yet... But will within 6 months to a year.

Wtf? I just did my front brakes and my rotors were fine. Why would you change your rotors with brake pads? (unless you grinded down the pads into metal an then used that metal to grind down your rotor...)

Wtf? I just did my front brakes and my rotors were fine. Why would you change your rotors with brake pads? (unless you grinded down the pads into metal an then used that metal to grind down your rotor...)

That is pretty standard among BMWs

Not saying you HAVE to do this, just like you dont HAVE to change your oil until 15k...

Good practice in BMWs has been to do the rotors with the pads, BMWs oem rotors are "thin" are not made to be turned down.

How would one know that they aren't warped or aren't "too thin". I can get a micrometer/calipers to measure thickness but what determines too thin? How thick is a new rotor to spec (to gauge life)

I'm at 60k and was planning to do a full brake job myself. Brakes work really well now (other than dust) and if I don't need to pay ~$80 per wheel for new rotors, I'd be happy.

You'd feel it if your rotors are warped because your whole car would be shaking when you applied the brakes. Your rotor won't get "thinner" or have any kind of damage under usual wear. I think your indy shop was just looking to make some more $ off of you.

The main reason people change rotors are because they wait too long to change the brake pads and they grind the rotors up. Or because they wash the car when the rotors are super hot and warp the rotors.

I'm at 102,300 miles (6 yrs) and the rotors are going to need to be replaced soon. Only replace your brake pads periodically when the car tells you to. Like Once every 18 months. Depends on how much and how hard you use your brakes, as always. Rotors will last a long time

+1. I was really debating whether or not I should have changed my rotors too with my last brake pad change (just clicked past 47k miles.) Ultimately I chose not to change them and they still feel great even after the brake pad change, granted I got fresh brake fluid, lines, and pads.

You'd feel it if your rotors are warped because your whole car would be shaking when you applied the brakes. Your rotor won't get "thinner" or have any kind of damage under usual wear. I think your indy shop was just looking to make some more $ off of you.

The main reason people change rotors are because they wait too long to change the brake pads and they grind the rotors up. Or because they wash the car when the rotors are super hot and warp the rotors.

BMW rotors use a very low carbon cast grey iron and are NOTORIOUSLY soft, and typically will wear below minimum thickness before the 2nd set of pads.

As to the OP's initial question about how long these rotors should last, there's no good answer, to be honest. If you drive 55mph, never go over 2,500 RPM, brake like you're afraid the brake pedal is going to bite you back...Let's just say I've seen factory rotors that have lasted over 100,000 miles before. Then again, if you're living life one traffic light at a time, DRAGS your left foot on the brake while you accelerate with the right? Those rotors will likely be done by 30,000 miles. Or if you go to about a dozen local high performance driving events at very brake demanding tracks like Auto Club Speedway, where you're slowing down from 125mph to 40mph repeatedly every 2 minutes, 10-12 times in a row? Don't expect it to last more than 20,000 miles.

So you see, it's all subjective to your driving style. I can tell you on AVERAGE they last anywhere between 1-2 pads per rotor, but more aggressive driving will shorten that timeframe dramatically, depending on what sort of brake compounds you're using.

__________________

The hell I don't! LISTEN, KID! I've been hearing that crap ever since I was at UCLA. I'm out there busting my buns every night! Tell your old man to drag Walton and Lanier up and down the court for 48 minutes!

BMW rotors use a very low carbon cast grey iron and are NOTORIOUSLY soft, and typically will wear below minimum thickness before the 2nd set of pads.

As to the OP's initial question about how long these rotors should last, there's no good answer, to be honest. If you drive 55mph, never go over 2,500 RPM, brake like you're afraid the brake pedal is going to bite you back...Let's just say I've seen factory rotors that have lasted over 100,000 miles before. Then again, if you're living life one traffic light at a time, DRAGS your left foot on the brake while you accelerate with the right? Those rotors will likely be done by 30,000 miles. Or if you go to about a dozen local high performance driving events at very brake demanding tracks like Auto Club Speedway, where you're slowing down from 125mph to 40mph repeatedly every 2 minutes, 10-12 times in a row? Don't expect it to last more than 20,000 miles.

So you see, it's all subjective to your driving style. I can tell you on AVERAGE they last anywhere between 1-2 pads per rotor, but more aggressive driving will shorten that timeframe dramatically, depending on what sort of brake compounds you're using.

Why not find out what the minimum-recommended, caliper thickness is, measure, and change if needed? Eyeballing or guessing isn't really the preferred method for determining whether you should change your rotors. Rotors are a wear item.

Why not find out what the minimum-recommended, caliper thickness is, measure, and change if needed? Eyeballing or guessing isn't really the preferred method for determining whether you should change your rotors. Rotors are a wear item.

Old thread bump.

This isnt a subjective question. You have to measure the rotor thickness.

I'm pushing 126,000 miles on my original rotors and pads. Starting at about 80,000 miles I started checking the rotor thickness myself because it didn't seem right that my original brakes were still good. Even today, my original rotors are slightly above minimum thickness and my pad sensors haven't been activated.

I ordered a new set of fronts and rears from getbmwparts.com just because, nothing lasts forever right? My new front rotors show the same minimum thickness as the originals on my car, 22.4mm. I measured the new rotors and they are 23.97mm according to my micrometer. So......over 6 years and 125K, I have lost about 1.5mm of rotor thickness on my OEMs. Can't wait to compare my original pads with my new pads to see how much they have worn. I'll try and post some measurements and pics.

And yes, I am a spirited driver who combines an equal amount of highway and stop and go city driving. Who cares about a little extra brake dust when the brakes last for 125k!! And before I get a bunch of replies saying you had to replace your brakes at 25k, 30k or 50k......did you actually measure the rotors and look at the pads yourself, or did you blindly rely on the stealerships recommendation?